Die set bushing retainer

ABSTRACT

A die set having bushings to guide the leader pins includes a bendable or breakable collar which bends or breaks in the event that the corresponding leader pin galls and freezes within the bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore of the punch holder to prevent damage to the die.

J aniszewski Mar. 18, 1975 DIE SET BUSHING RETAINER [76] Inventor: Kasimir Janiszewski, 1 1908 W.

Loomis Rd., Franklin, Wis. 53132 2,869,177 1/1959 Jurgeleit 100/214 FOREIGN PATENTS OR APPLICATIONS 262,273 12/1926 Llr1i tedKingdom ..72/455 F' 1 [22] Oct 24 1973 Primary Examiner-C. W. Lanham [2]] Appl. N0.: 409,230 Assistant Examiner-E. M. Combs Attorney, Agent, or Firm-Henry C. Fuller [52] U.S. Cl. 72/456, 308/4 C 51 1m. 01 ..B21d 37/10, B21 13/04 1 A T 58] Field 6: Search 72/31, 455, 456; 100/53, A @116 Set havmg bushmgs to guide the leader P 100/214; 3 4 C cludes a bendable or breakable collar which bends or breaks in the event that the corresponding leader pin 5 References Cited galls and freezes within the bushing sleeve, thereby UNn-ED STATES PATENTS permitting the frozen bushing sleeve to reciprocate 2 148 855 2/1939 C o loo/7M within the corresponding bore of the punch holder to an" n 2,627,313 2/1953 Marsilius... prevent damage to the 2,837,944 6/1958 Albers 100/214 7 Claims, 6 Drawing Figures "150 l a 62 i [i v 1 DIE SET BUSHING RETAINER BACKGROUND OF THE INVENTION This invention relates to die sets of the type having a die shoe for "receiving and supporting a die and'a punch holder mounted for reciprocal movement toward and away from the die shoe. A plurality of leader pins are each attached at one end to the die shoe and extend therefrom toward the punch holder. A plurality of bushing sleeves are seated within corresponding bores in the punch holder to slidably receive the leader pins and guide the punch holder in its reciprocal movement toward and away from the die shoe. In such die sets, a serious problem arises when one of the leader pins galls and freezes in the corresponding bushing sleeve. This causes the punch holder to bend and can cause breakage of the die parts.

The principal object of this invention is to provide an improved die set which will not injure the die if one of the leader pins galls and freezes in its bushing sleeve.

SUMMARY OF THE INVENTION A punch holder is mounted for reciprocal movement toward and away from a dieshoe. A plurality of leader pins are each attached at one end to the die shoe and each slidably engage a corresponding-bushing sleeve in the punch holder. Each bushing sleeve is seated in a corresponding bore in the punch holder. The outside diameter of each bushing sleeve is small enough to permit the sleeve to be reciprocated within its bore. An enlarged collar is formed on one end of the bushing sleeve and is dimensioned to secure the bushing sleeve within the bore. The portion of the bushing sleeve adjacent to the collar is distortable so as to permit the collar to be bent or broken off in the event that the corresponding leader pin galls and freezes within the bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within its bore to prevent damage to the punch holder and die.

Further objects, features and advantages of the invention will become apparent from the following disclosure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of one illustrative die set of this invention.

FIG. 2 is an enlarged fragmentary vertical sectional view taken on the line 22 of FIG. 1.

FIG. 3 is an enlarged fragmentary vertical sectional view showing the groove between a bushing sleeve-and its collar and the chip which is sheared off the interior of the bore when the collar is press fitted therewithin.

FIG. 4 is an enlarged fragmentary vertical sectional view similar to FIG. 2 showing the collar broken off from its bushing and the bushing moved downwardly within its bore.

FIG. 5 is an enlarged fragmentary vertical sectional view similar to FIG. 2 showing a second embodiment of the invention in which the collar is a washer that is spot welded to the end of the bushing sleeve.

FIG. 6 is an enlarged fragmentary cross sectional prospective view ofa third embodiment of the invention in which the collar portion of the bushing is bendable.

DESCRIPTION OF THE PREFERRED EMBODIMENT exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

FIG. I is an elevation view of one illustrative embodiment of this invention. A die shoe 10 supports a die 12 which is attached to the die shoe by conventional means not shown in the drawings. Two leader pins 14 are attached at one end to die shoe l0 and extend upwardly therefrom. The lower end of each leader pin 14 is necked down and extends through a bore 16 in die shoe 10. The lower end of the necked down portion is threaded to receive a nut 18 which clamps leader pin 14 in position against the upper edge of the bore 16.

A punch holder 20 is movably mounted for reciprocal movement toward Vandaway from die shoe I0 and carries a punch 22 which interacts with the die 12. Punch holder 20 is moved by a ram 24 which is attached to a pressure plate 26 on the top of punch holder 20. Ram 24 is operated by conventional means not shown in the drawings.

Two bushingsleeves 28 are seated in bores 30 in punch holder 20. The inner cylindrical surface 32 of each bushing sleeve 28 is dimensionedto slidably receive a corresponding leader pin 14 to guide punch holder 20 in its reciprocal movement toward and away from die shoe 10.

The outside diameter of each bushing sleeve 28 is approximately equal to the diameter of the bore 30 within which it is seated so as to permit bushing sleeve 28 to be moved up and down within bore 30. If desired, the outside diameter of each bushing sleeve 28 may be slightly larger than the diameter of bore 30 to give a slight press fit for bushingsleeves 28, but the difference of diameter must not be large enough to prevent bushing sleeves 28 from being moved up and down within bores 30 by the pressure of ram 24 for reasons that will be discussed hereinafter.

In accordance with this invention, an enlarged collar which is distortable is provided at the upper end of each bushing sleeve 28 tosecure the bushing sleeve 28 within its bore 30. Distortable as used hereinmeans that the collar may be either bent or broken to free the bushing sleeve for recriprocation within its bore 30.

Referring to FIGS. 2 and 3, in one embodiment of the invention, an enlarged collar or flange 34 is formed on the upper end of each bushing sleeve 28. The outside diameter of collar 34 is larger than the diameter of bore 30 to provide a conventional press fit between collar 34 and bore 30 when the bushing sleeves 28 are forced into bores 30. An annular groove .36 is formed around the upper end of each bushing sleeve 28 adjacent to the lower edge of collar 34. Groove 36 provides clearance for the chip 38 (FIG. 3) which is sheared off the upper end of bore 30 when the collar 34 is press fitted therewithin. Groove 36 also provides a weakened region or frangible zone at the end of bushing sleeve 28 along which the sleeve 28 may be fractured as described hereinafter.

In the normal operation of the above-described die set, the bushing sleeves 28 slide over the leader pins 14 and guide the punch holder 20 in its reciprocal motion toward and away from die shoe 10. In the event that one of the leader pins 14 galls and freezes in its bushing sleeve 28, the bushing sleeve 28 is prevented from moving upwardly out of its bore 30 by the ram pressure wardly from the groove 36 to the top end of bushing sleeve 28. This frees the bushing sleeve 28 from its interference fit with bore 30 and allows the sleeve 28 to be moved up and down within bore 30. This obviates bending of punch holder 20 and'breakage of die 12 due to the frozen bushing 28.

ln the operation of this embodiment, the groove 36 serves both as a relief space for chip 38 and as a means of weakening the end of sleeve 28 so that it will fracture along line 40 in response to the upward pressure applied to punch holder 20 by the return stroke of ram 24 when the sleeve 28 is frozen to leader pin 14. Groove 36 also forms a sharp shoulder 37 (FIG. 3) where it intersects the surface of collar 34. Shoulder 37 cuts the chip 38 when the collar 34 is press fitted into bore 30.

FIG. shows a modified structure in which a bushing sleeve 42 has an enlarged washer 44 spot welded at 45 to its upper end to form a collar 46 which performs the same function as the collar 34 described above. The outside diameter of bushing sleeve 42 is equal to or only slightly larger than the diameter of bore 30 to permit sleeve 42 to be reciprocated within bore 30. The outside diameter of collar 46 is larger than the diameter of bore 30 to provide a conventional press fit thereinbetween. A taper 48 on the upper end of bushing sleeve 42 provides a relief space for the chips formed when collar 46 is press fitted into bore 30. The lower outside edge 47 of washer 44 is preferably sharp enough to cut a chip similar to chip 38 in FIG. 3. In this embodiment, the washer 44 separates from bushing sleeve 42 at the spot welds 45 that hold the two together. The amount of pressure required to separate the washer 44 from sleeve 42 depends upon the number of spot welds 45 and can be controlledby varying the number of spot welds 45. The number of spot welds 45 is selected so that the fracturing pressure falls within the range of pressure generated by the return stroke of ram 24 when leader pin 14 is frozen to bushing sleeve 42. In this embodiment the spot welds 45 provide the weakened portion of bushing sleeve 42 adjacent to the collar 46.

FIG. 6 shows a third embodiment of the invention in which the collar is bendable instead of being breakable. In this embodiment, a bushing sleeve 50 is seated within a bore 52 in punch holder 54. Bushing sleeve 50 has an enlarged collar 56 which has a lower beveled surface 58 and an upper beveled surface 60. Lower beveled surface 58 mates with a countersunk portion 62 of bore 52 and normally prevents the bushing sleeve 50 from being moved downwardly. The upper surface of punch holder 54 is upset at 64 to prevent the bushing sleeve 50 from being moved upwardly. Although only one upset 64 is shown in FIG. 6, it will be understood that a plurality of such upsets are spaced around the petime to bend inwardly until the'outside edge 68 of collar 56 lies within the bore 52. The entire bushing sleeve 50 may then be reciprocated within bore 52 to avoid damage to the die parts. i

What is claimed is: 1. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality of leader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushing sleeves each seated in a corresponding bore in said punch holder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated within the corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore and each collar being seated within the corresponding bore each of said bushing sleeves having an annular groove at the boundary between said sleeve and said enlarged collar, and the portion of each bushing sleeve adjacent to said 'collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe.

2. The die set defined in claim 1 wherein the outside diameter of each collar is larger than the diameter of the corresponding bore and the collar is press fitted into the corresponding bore to secure the bushing sleeve within said bore, and wherein the portion of each bushing sleeve adjacent to said collar is frangible under pressure to permit the collar to be broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe.

3. The die set defined in claim 1 wherein the outside diameter of each collar is larger than the diameter of the corresponding bore, and wherein the portion of each bushing sleeve adjacent to said collar is bendable under pressure to permit the collar to be bent inwardly in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corre sponding bore to prevent damage to a die attached to said die shoe.

4. The die set defined in claim 2 wherein said collar is integral with said bushing sleeve.

5. The die set defined in claim 2 wherein said collar is separate from said bushing sleeve and is attached thereto by welding.

6. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality of leader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushing sleeves each seated in a corresponding bore in said punch holder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated withinthe corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore, and the portion of each bushing sleeve adjacent to said collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve,

thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and wherein the outside diameter of each collar is larger than the diameter of the corresponding bore, and wherein the portion of each bushing sleeve adjacent to said collar is bendable under pressure to permit the collar to be bent inwardly in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and said collar having an outer surface having upper and lower beveled surfaces and wherein the edge of said bore adjacent to said collar is countersunk to form a sloping surface which mates with the lower beveled surface of said collar, and wherein portions of said punch holder are upset around the periphery of said countersunk portion to prevent said bushing sleeve from being moved upwardly.

7. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality ofleader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushingsleeves each seated in a corresponding bore in said punchholder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated within the corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore, and the portion of each bushing sleeve adjacent to said collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and wherein the outside diameter of eachcollar is larger than the diameter of the corresponding bore so that the collar can be press fitted into the corresponding bore to secure the bushing sleeve within said bore, and wherein the portion of each bushing sleeve adjacent to said collar is frangible under pressure to permit the collar to be broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the cor responding bore to prevent damage to a die attached to said die shoe, said collar being separate from said bushing sleeve and attached thereto by welding, and said outer edge of said bushing sleeve adjacent to said collar being tapered to form an annular groove in said bushing sleeve adjacent to said collar. 

1. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality of leader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushing sleeves each seated in a corresponding bore in said punch holder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated within the corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore and each collar being seated within the corresponding bore each of said bushing sleeves having an annular groove at the boundary between said sleeve and said enlarged collar, and the portion of each bushing sleeve adjacent to said collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe.
 2. The die set defined in claim 1 wherein the outside diameter of each collar is larger than the diameter of the corresponding bore and the collar is press fitted into the corresponding bore to secure the bushing sleeve within said bore, and wherein the portion of each bushing sleeve adjacent to said collar is frangible under pressure to permit the collar to be broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe.
 3. The die set defined in claim 1 wherein the outside diameter of each collar is larger than the diameter of the corresponding bore, and wherein the portion of each bushing sleeve adjacent to said collar is bendable under pressure to permit the collar to be bent inwardly in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe.
 4. The die set defined in claim 2 wherein said collar is integral with said bushing sleeve.
 5. The die set defined in claim 2 wherein said collar is separate from said bushing sleeve and is attached thereto by welding.
 6. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality of leader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushing sleeves each seated in a corresponding bore in said punch holder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated within the corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore, and the portion of each bushing sleeve adjacent to said collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and wherein the outside diameter of each collar is larger than the diameter of the corresponding bore, and wherein the portion of each bushing sleeve adjacent to said collar is bendable under pressure to permit the collar to be bent inwardly in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and said collar having an outer surface having upper and lower beveled surfaces and wherein the edge of said bore adjacent to said collar is countersunk to form a sloping surface which mates with the lower beveled surface of said collar, and wherein portions of said punch holder are upset around the periphery of said countersunk portion to prevent said bushing sleeve from being moved upwardly.
 7. An improved die set comprising a die shoe for receiving and supporting a die, a punch holder mounted for reciprocal motion toward and away from said die shoe, a plurality of leader pins each attached at one end to said die shoe and extending therefrom toward said punch holder, a plurality of bushing sleeves each seated in a corresponding bore in said punch holder for slideably receiving a corresponding leader pin to guide said punch holder in its reciprocal motion toward and away from said die shoe, the outside diameter of each bushing sleeve being of such size as to permit the bushing sleeve to be axially reciprocated within the corresponding bore, an enlarged collar on one end of each bushing sleeve, each collar being dimensioned to secure the corresponding bushing sleeve within said bore, and the portion of each bushing sleeve adjacent to said collar being distortable under pressure to permit the collar to be bent or broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, and wherein the outside diameter of each collar is larger than the diameter of the corresponding bore so that the collar can be press fitted into the corresponding bore to secure the bushing sleeve within said bore, and wherein the portion of each bushing sleeve adjacent to said collar is frangible under pressure to permit the collar to be broken off in the event that the corresponding leader pin freezes within said bushing sleeve, thereby permitting the frozen bushing sleeve to reciprocate within the corresponding bore to prevent damage to a die attached to said die shoe, said collar being separate from said bushing sleeve and attached thereto by welding, and said outer edge of said bushing sleeve adjacent to said collar being tapered to form an annular groove in said bushing sleeve adjacent to said collar. 